Methods and system for a battery

ABSTRACT

Various embodiments of the present technology may provide methods and system for a battery. The system may provide a fuel gauge circuit configured to select an energy curve from a plurality of energy curves and determine a remaining energy value based on the selected energy curve and a computed remaining capacity of the battery. The fuel gauge circuit controls a current to a load based on the remaining energy value.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication No. 62/899,832, filed on Sep. 13, 2019, the entire contentsof which is incorporated herein by reference.

BACKGROUND OF THE TECHNOLOGY

“Battery capacity” is a measure (typically in ampere-hours) of thecharge stored by the battery and is determined by the mass of activematerial contained in the battery. The remaining battery capacity mayprovide an indication of “run-time” (i.e., lifespan) of the battery,which reflects the amount of time the battery will continue to providepower before it dies. An accurate estimate of the run-time is desired toprovide alerts to a user as to the remaining life of the battery. Theremaining battery capacity, however, is not always equal to theremaining energy because the elapsed time and battery current used tocompute the remaining capacity may not be the same as the elapsed timeused to the compute the remaining energy (which is calculated using anelapsed time, current, and voltage). Therefore, it may be desirable todetermine the run-time of the battery based on the remaining energy, inaddition to the remaining capacity.

SUMMARY OF THE INVENTION

Various embodiments of the present technology may provide methods andsystem for a battery. The system may provide a fuel gauge circuitconfigured to select an energy curve from a plurality of energy curvesand determine a remaining energy value based on the selected energycurve and a computed remaining capacity of the battery. The fuel gaugecircuit controls a current to a load based on the remaining energyvalue.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

A more complete understanding of the present technology may be derivedby referring to the detailed description when considered in connectionwith the following illustrative figures. In the following figures, likereference numbers refer to similar elements and steps throughout thefigures.

FIG. 1 is a block diagram of a battery system in accordance with anexemplary embodiment of the present technology;

FIG. 2 illustrates voltage and current characteristics of a battery inaccordance with an exemplary embodiment of the present technology;

FIG. 3A is a graph illustrating a constant voltage of a dischargingbattery;

FIG. 3B is a graph illustrating remaining energy and remaining state ofcharge of a discharging battery with constant current and constantvoltage;

FIG. 4A is a graph illustrating a variable voltage of a dischargingbattery;

FIG. 4B is a graph illustrating remaining energy of a dischargingbattery with constant current and variable voltage;

FIG. 5 is a graph illustrating remaining energy over time with variablevoltage and remaining energy over time with constant voltage;

FIG. 6 is a graph illustrating remaining energy over time with variousvoltage conditions as a function of RSOC in accordance with an exemplaryembodiment of the present technology; and

FIG. 7 is a flow chart for operating the battery system in accordancewith an exemplary embodiment of the present technology.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

The present technology may be described in terms of functional blockcomponents and various processing steps. Such functional blocks may berealized by any number of components configured to perform the specifiedfunctions and achieve the various results. For example, the presenttechnology may employ various voltage sensors, current sensors, coulombcounters, logic gates, timers, memory devices, semiconductor devices,such as transistors and capacitors, and the like, which may carry out avariety of functions. In addition, the present technology may beintegrated in any number of electronic systems, such as automotive,aviation, “smart devices,” portables, e-cigarettes, and consumerelectronics, and the systems described are merely exemplary applicationsfor the technology.

Methods and system for a battery according to various aspects of thepresent technology may operate in conjunction with any suitableelectronic system and/or device, such as “smart devices,” wearables,consumer electronics, portable devices, battery-powered vehicles, andthe like. Referring to FIG. 1, an exemplary system 100 may be integratedin an electronic device (not shown), such as an e-cigarette, powered bya rechargeable battery 101, such as a lithium ion battery. For example,in various embodiments, the battery 101 may operate in conjunction witha charger 105 to provide power to a load 160, such as a heating coil inthe e-cigarette.

The system 100 may further comprise a fuel gauge circuit 110 to managevarious battery operations and monitor various battery conditions. Forexample, the fuel gauge circuit 110 may be configured to measure avoltage V_(B) of the battery 101, measure a current I_(DD) of thebattery 101, compute a remaining capacity (also expressed as apercentage and referred to as the relative state of charge RSOC) of thebattery 101, compute a state of health (SOH) of the battery 101, andestimate a lifespan of the battery 101.

In addition, the fuel gauge circuit 110 may be configured to storevarious battery data. For example, the fuel gauge circuit 110 may storepredetermined battery characteristics, such as a plurality of energycurves that describe a relationship between a remaining energy of thebattery at different voltage levels as a function of the state of charge(i.e., RSOC) of the battery 101. The fuel gauge circuit 110 may alsostore predetermined values, such as a predetermined threshold voltagevalue VIII

In an exemplary embodiment, the fuel gauge circuit 110 may comprise atemperature sensor 120 to measure a temperature T of the battery 101.The temperature sensor 120 may comprise a thermistor (not shown) thatgenerates a signal and an analog-to-digital converter (not shown) toconvert the signal to a voltage which corresponds to the temperature Tof the battery 101. The temperature sensor 120 may, however, compriseany appropriate sensor or other device or system for generating a signalcorresponding to the temperature of the battery 101.

In an exemplary embodiment, the fuel gauge circuit 110 may comprise avoltage sensor 130 to measure the voltage V_(B) of the battery 101. Thevoltage sensor 130 may be connected to the battery 101 and may compriseany circuit and/or device suitable for measuring a voltage potential.

In an exemplary embodiment, the fuel gauge circuit 110 may comprise acurrent sensor 135 to measure the current I_(DD) to/from the battery 101and the load 160. The current sensor 135 may operate in conjunction witha sense resistor 155, wherein the current senor 135 measures a change involtage across the sense resistor 155 to determine the current.

In an exemplary embodiment, the fuel gauge circuit 110 may comprise acalculation circuit 125 to compute the remaining capacity RC (measuredin ampere-hours) and/or the RSOC (the remaining capacity RC representedas a percentage). The calculation circuit 125 may be connected to thevoltage sensor 130 to receive the measured voltage V_(B) data. Thecalculation circuit 125 may also be connected to the current sensor 135to receive the measured current data I_(DD). The calculation circuit 125may be configured to compute the remaining capacity according to themeasured voltage V_(B) and the measured current. The calculation circuit125 may compute the remaining capacity of the battery 101 according toconventional “voltage-based” methods and techniques.

In an exemplary embodiment, the fuel gauge circuit 110 may comprise amemory 140 to store the known battery characteristics and profile dataof the battery 101, such as a plurality of energy curves as a functionof voltage and remaining capacity (e.g., as illustrated in FIG. 6). Theenergy curves may be stored in a look-up table or any other data storagesuitable for storing relational data.

The memory 140 may also store various previously- and currently-computedor measured variables, such as the threshold voltage V_(TH), elapsedtime values, measured battery voltage values, predetermined time values(such as a recovery time RT) and the like.

The memory 140 may comprise any number of storage devices, such asregisters, a flash memory device, EEPROM (electrically erasableprogrammable read-only memory), ROM (read only memory), and RAM (randomaccess memory), and the like.

In an exemplary embodiment, the fuel gauge circuit 110 may comprise atimer 145 to measure or otherwise count an amount of elapsed time t froma starting time. The timer 145 may comprise any circuit and/or devicesuitable for measuring/counting an amount of time elapsed from astarting time.

In an exemplary embodiment, the fuel gauge circuit 110 may comprise alogic circuit 150 to perform various computations and/or estimate thelifespan of the battery 101. According to an exemplary embodiment, thelogic circuit 150 may be configured to determine a remaining energy ofthe battery 101 based on the plurality of energy curves, the remainingcapacity (i.e., RSOC), and the voltage V_(B) of the battery 101.

The logic circuit 150 may be configured to receive the computedremaining capacity (i.e., RSOC) from the calculation circuit 125. Thelogic circuit 150 may also be configured to access various data from thememory 140, such as data from the plurality of energy curves. Inaddition, the logic circuit 150 may be configured to communicate withthe timer 145. For example, the logic circuit 150 may be configured toreset and restart the timer 145 and/or receive the elapsed time value t.

According to an exemplary embodiment, the logic circuit 150 may beconfigured to estimate the lifespan of the battery 101 based on measuredparameters and/or known parameters, such as the remaining capacity(i.e., RSOC), the voltage V_(B) of the battery 101, and the remainingenergy of the battery 101.

The logic circuit 150 may comprise any number of circuits, systems,and/or logic gates to perform the desired computations, as describedabove. For example, the logic circuit 150 may comprise a fieldprogrammable gate array, and application specific integrated circuit,and the like.

In general, and referring to FIGS. 3A-3B and 5, if the voltage of thebattery 101 is constant over time (during a discharge period) and thecurrent is also constant during that same period, the remaining energyof the battery 101 will be the same as the remaining capacity (i.e., SOCor RSOC) and both will decrease linearly over time. However, andreferring to FIGS. 4A-4B, when the voltage of the battery is notconstant during a discharge period, then the remaining energy of thebattery 101 is not equal to the remaining capacity and does not decreaselinearly. In most applications, the battery voltage is not constantduring a discharge period, therefore, the remaining capacity is notequal to the remaining energy of the battery 101, and the remainingcapacity may not provide an accurate estimate of the lifespan of thebattery 101.

In addition, and referring to FIG. 2, during operation, the load 160 maydraw a large current from the battery 101. When this occurs, the voltageof the battery 101 drops. If the voltage drops below the thresholdvoltage V_(TH), the voltage of the battery 101 does not return to itsrated voltage right away, but instead recovers after some period oftime. Therefore, the amount of power that the battery 101 is capable ofproviding may be less than expected.

In an exemplary operation, and referring to FIGS. 1 and 5-7, the system100 may be set with the threshold voltage V_(TH) (700). For example, thememory 140 may be used to store the threshold voltage V_(TH). The valueof threshold voltage V_(TH) may be based on the particularcharacteristics of the battery 101 and/or particular application. Forexample, the threshold voltage V_(TH) may be determined during a testingperiod of the battery 101 in an intended application, such as ane-cigarette.

The system 100 may then set the recovery time RT (e.g., 3600 seconds)(705). For example, the memory 140 may be used to store the recoverytime RT. The value of the recovery time RT may be based on theparticular characteristics of the battery 101 and/or the particularapplication. For example, the recovery time may be determined during atesting period of the battery 101 in an intended application, such as ane-cigarette.

The system 100 may then measure the battery voltage Vs (710), forexample, using the voltage sensor 130 and/or other conventional voltagemeasuring techniques or methods. The voltage sensor 130 may thentransmit the measured voltage V_(B) to the logic circuit 150.

The logic circuit 150 may then determine if the measured voltage V_(B)is less than the threshold voltage V_(TH). For example, the logiccircuit 150 may retrieve the threshold voltage V_(TH) from the memory140 and compare it to the measured voltage V_(B). If the measuredvoltage V_(B) is not less than the threshold voltage, then the system100 may re-measure the battery voltage V_(B).

If the measured voltage V_(B) is less than the threshold voltage V_(TH),then the system 100 may calculate the remaining capacity (i.e., RSOC) ofthe battery 101 (720) for example, using the calculation circuit 125.The calculation circuit 125 may transmit the measured RSOC to the logiccircuit 150.

In addition, if the measured voltage V_(B) is less than the thresholdvoltage V_(TH), then the logic circuit 150 may reset the timer 145 andstart counting a new elapsed time t_(N)(720).

The system 100 may then utilize the plurality of energy curves, themeasured RSOC, and the battery voltage V_(B) to determine the remainingenergy of the battery 101 (725). For example, the logic circuit 150 mayutilize the measured battery voltage V_(B) to determine a particularenergy curve, from the plurality of energy curves, and then use themeasured RSOC to determine the remaining energy of the battery 101. Forexample, and referring to FIG. 6, if the battery voltage V_(B) is withina first voltage range (variable voltage 1), the ‘energy 1’ curve isselected. If the measured RSOC is 50%, then based on the ‘energy 1’curve, the remaining energy is approximately 45%. The system 100 maythen utilize the remaining energy to estimate the lifespan of thebattery 101 (730).

The system 100 may utilize the determined remaining energy to controlthe current from the battery 101 to the load 160, such as to conservepower and lengthen the life of the battery 101. For example, the logiccircuit 150 may be configured to control (turn ON and OFF) one or moreswitches connected between the battery 101, the charger 105, and theload 160, which may be arranged to prevent current from flowing to theload 160 or allow current to flow to the load 160.

In addition, the system 100 may compare the new elapsed time t_(N) tothe recovery time RT. Once the elapsed time t_(N) is equal to therecovery time RT, the system 100 may continue to use the measuredremaining capacity (i.e., RSOC) to determine the lifespan of the battery101.

In the foregoing description, the technology has been described withreference to specific exemplary embodiments. The particularimplementations shown and described are illustrative of the technologyand its best mode and are not intended to otherwise limit the scope ofthe present technology in any way. Indeed, for the sake of brevity,conventional manufacturing, connection, preparation, and otherfunctional aspects of the method and system may not be described indetail. Furthermore, the connecting lines shown in the various figuresare intended to represent exemplary functional relationships and/orsteps between the various elements. Many alternative or additionalfunctional relationships or physical connections may be present in apractical system.

The technology has been described with reference to specific exemplaryembodiments. Various modifications and changes, however, may be madewithout departing from the scope of the present technology. Thedescription and figures are to be regarded in an illustrative manner,rather than a restrictive one and all such modifications are intended tobe included within the scope of the present technology. Accordingly, thescope of the technology should be determined by the generic embodimentsdescribed and their legal equivalents rather than by merely the specificexamples described above. For example, the steps recited in any methodor process embodiment may be executed in any order, unless otherwiseexpressly specified, and are not limited to the explicit order presentedin the specific examples. Additionally, the components and/or elementsrecited in any apparatus embodiment may be assembled or otherwiseoperationally configured in a variety of permutations to producesubstantially the same result as the present technology and areaccordingly not limited to the specific configuration recited in thespecific examples.

Benefits, other advantages and solutions to problems have been describedabove with regard to particular embodiments. Any benefit, advantage,solution to problems or any element that may cause any particularbenefit, advantage or solution to occur or to become more pronounced,however, is not to be construed as a critical, required or essentialfeature or component.

The terms “comprises”, “comprising”, or any variation thereof, areintended to reference a non-exclusive inclusion, such that a process,method, article, composition or apparatus that comprises a list ofelements does not include only those elements recited, but may alsoinclude other elements not expressly listed or inherent to such process,method, article, composition or apparatus. Other combinations and/ormodifications of the above-described structures, arrangements,applications, proportions, elements, materials or components used in thepractice of the present technology, in addition to those notspecifically recited, may be varied or otherwise particularly adapted tospecific environments, manufacturing specifications, design parametersor other operating requirements without departing from the generalprinciples of the same.

The present technology has been described above with reference to anexemplary embodiment. However, changes and modifications may be made tothe exemplary embodiment without departing from the scope of the presenttechnology. These and other changes or modifications are intended to beincluded within the scope of the present technology, as expressed in thefollowing claims.

The invention claimed is:
 1. An apparatus for monitoring a battery,comprising: a voltage sensor configured to measure a voltage of thebattery; a calculation circuit configured to measure a remainingcapacity of the battery according to the measured voltage; a memoryconfigured to store: a predetermined voltage threshold; andpredetermined battery data comprising a plurality of energy curves; anda logic circuit configured to: determine if the measured voltage of thebattery is less than the predetermined voltage threshold; select oneenergy curve from the plurality of energy curves based on the measuredvoltage of the battery when the measured voltage is determined to beless than the predetermined voltage; and select a remaining energy valuefrom the selected energy curve based on the measured remaining capacity.2. The apparatus according to claim 1, further comprising a timerconfigured to count to a predetermined time.
 3. The apparatus accordingto claim 2, wherein the logic circuit is further configured to reset thetimer and restart the timer to count an elapsed time if the measuredbattery voltage is less than the predetermined threshold.
 4. Theapparatus according to claim 2, wherein the battery recovers to aninitial voltage after the predetermined time has elapsed.
 5. Theapparatus according to claim 1, wherein each energy curve from theplurality of energy curves comprises remaining energy values andcorresponding remaining capacity values.
 6. The apparatus according toclaim 1, wherein the memory is further configured to storepreviously-measured voltage data.
 7. The apparatus according to claim 6,wherein the logic circuit is further configured to estimate a lifespanof the battery based on the previously-measured voltage data and theselected energy curve.
 8. The apparatus according to claim 1, whereinthe logic circuit is further configured to generate a modified remainingcapacity value based on the measured remaining capacity and the selectedenergy curve.
 9. A method for monitoring a battery, comprising: measurea voltage of the battery; compute a remaining capacity of the batterybased on the measured voltage; determine if the measured voltage is lessthan a predetermined threshold; select an energy curve from a pluralityof energy curves based on the measured voltage of the battery when themeasured voltage is determined to be less than the predeterminedvoltage; and determine a remaining energy value based on the selectedenergy curve and the computed remaining capacity.
 10. The methodaccording to claim 9, further comprising counting for a predeterminedtime period if the measured voltage is less than the predeterminedthreshold.
 11. The method according to claim 10, further comprisinggenerating a modified remaining capacity based on the computed remainingcapacity and the selected energy curve.
 12. The method according toclaim 9, further comprising utilizing the remaining energy valueestimate a lifespan of the battery.
 13. A system, comprising: a battery;a fuel gauge circuit connected to the battery and configured to: measurea voltage of the battery; compute a remaining capacity of the batterybased on the measured voltage; store: a predetermined voltage threshold;and predetermined battery data comprising a plurality of energy curves;determine if the measured voltage of the battery is less than thepredetermined voltage threshold; select one energy curve from theplurality of energy curves based on the measured voltage of the batterywhen the measured voltage is determined to be less than thepredetermined voltage; and determine a remaining energy value based onthe selected energy curve and the computed remaining capacity; and aload connected to the battery and the fuel gauge, wherein the fuel gaugecontrols a current to the load based on the remaining energy value. 14.The system according to claim 13, wherein the fuel gauge circuit isfurther configured to count to a predetermined time.
 15. The systemaccording to claim 14, wherein the fuel gauge circuit is furtherconfigured to re-start counting if the measured battery voltage is lessthan the predetermined threshold.
 16. The system according to claim 13,wherein each energy curve from the plurality of energy curves comprisesremaining energy values and corresponding remaining capacity values. 17.The system according to claim 13, wherein the fuel gauge circuit isfurther configured to generate a modified remaining capacity value basedon the measured remaining capacity and the selected energy curve. 18.The system according to claim 13, wherein the fuel gauge circuit isfurther configured to estimate a lifespan of the battery based on theremaining energy value.